Now we can use the Symanzik formula [1]}, [2]},
\(\int _0^{\infty } \int ^{\infty }_{0}\prod _{i=1}^n{\mathrm {d}t_i\over t_i}t_i^{\Delta _i}{\rm e}^{\sum _{i<j}^nt_it_jQ_{ij}}={1\over 2(2\pi i)^{n(n-3)\over 2}}\int _{\Sigma _n}\prod _{i<j}^n\Gamma (\delta _{ij})(Q_{ij})^{-\delta _{ij}}\,,\) 
